All the resources published/posted on MathCity.org are sent by different people to help the other people for the promotion of mathematics. These are open educational resources (OER).
OER are teaching, learning, and research resources that reside in the public domain or have been released under an intellectual property license that permits their free use or re-purposing by others. Open educational resources include full courses, course materials, modules, textbooks, streaming videos, tests, software, and any other tools, materials, or techniques used to support access to knowledge. (see more at wikipedia or creative commons.
With our aim of promotion of mathematics, we believe on fair use of resources/contents and fair distribution and propagation of resources/content. Copyright infringement or to break copyright law or piracy is not our policy and we are very strict for such type of issue or any other related to this.
If you think that there is a material/contents posted on MathCity.org, which is unauthorized copying of copyrighted material or which is an act of copyright infringement, then please contact at “firstname.lastname@example.org” with details.